The invention relates generally to signal analysis devices and, more specifically, to a method and apparatus for representing complex vector data.
A common practice in the field of communication system measurement is to display a time-varying complex signal vector by plotting the real component versus the imaginary component on a Cartesian coordinate system. Such a display is frequently referred to as a polar display, independent of whether Cartesian or polar axes are used. For example, using a representative complex signal S(t)=I(t)+j*Q(t), the values I(t) and Q(t) are both plotted parametrically against time. FIGS. 1A and 1B show some typical polar displays. FIG. 1A shows a polar display that is of short enough duration that the vector trajectory can be followed. FIG. 1B shows a longer vector record, in which the gross features and trends can be discerned but the path of the vector cannot be followed due to the number of overlapping lines displayed.
These and other deficiencies of the prior art are addressed by the present invention of a method and apparatus for representing complex vector signals or data. The invention advantageously allows very long records (i.e., vector data accumulated over a relatively long time period) to be viewed in a manner conveying to the viewer useful information regarding the signal density of the vector signal in various regions of a polar plane.
A method according to an embodiment of the invention for representing a modulated signal vector comprises determining complex coordinates for the signal vector where the complex coordinates define respective locations on a complex plane that is logically segmented into a plurality of regions, and by generating, for each logical region, a respective signal density indicative magnitude value to form a histogram of the logical regions and their respective magnitude values.